The present process comprises reacting acrylic acid with certain oxazoline monomers. Suprisingly few reactions are found in the literature which describe the reaction of acrylic acid with any oxazoline and those that are described produce products which are totally different from those described hereafter.
E. M. Fry, Journal of Organic Chemistry, 15, 802 (1950) and T. Kagiya et al, Polymer Letters, 4, 257 (1966) have shown that oxazoline rings are opened by carboxylic acids, thus producing the corresponding esters of the acid. Several cross-linking reactions have been described in the art wherein compounds (including polymers) bearing pendant carboxyl groups were reacted with compounds bearing 2 or more oxazoline groups, and vice versa, to form many useful cross-linked products.
Dowbenko reacted alkenoic acids (e.g., acrylic acid) with a 5-hydroxyalkyl-2-oxazoline and thus produced an alkenoic ester. Reaction occurred between the carboxyl group of the alkenoic acid and the hydroxyalkl group on the oxazoline reactant. The oxazoline ring remained intact in the process.
Riemhofer et al (USP 3,535,291) prepared a heat-curable vinyl-addition copolymer by reacting a 2-alkenyl-2-oxazoline with an alkenoic acid in the pressure of various amines. Again, the oxazoline ring remained intact in the process.
Another ring-preserving reaction is described by Tomalia in a commonly-owned U.S. patent application Ser. No. 489,382 filed July 17, 1974. Tomalia reacted equal molar amounts of an alkenoic acid with a bis-oxazoline. The product thus obtained was an acrylic ester having a pendant oxazoline group.
Thill, et. al. reacted a polymer bearing pendent-oxazoline groups with acrylic or methacrylic acid in a commonly-owned U.S. patent application Ser. No. 443,265 filed Feb. 19, 1974. The products thus produced are polymers bearing a plurality of pendent amide-ester groups.
All of the above reaction products described above are dissimilar to those defined hereafter.